Ricardo Morales started mining Bolivia's Cerro Rico when he was 12, and he's proud of the mountain's majestic history. "It's said that the silver taken from here could have built a bridge from the peak to Spain's palace door," boasts the raspy-voiced Morales, 52, standing at the entrance to his mine some 14,000 feet (4,200 meters) above sea level. But today, after almost 500 years of non-stop extraction, the Cerro Rico's grandeur is collapsing -- literally, like a titanic souffle. Earlier this year, a 3,767-sq-ft (339-sq-m) crater opened near the mountain's summit, and geologists warn of more implosions to come.

Yet that's not the worst part. Even though much of the exhausted Cerro Rico seems set to give way, miners like Morales insist on staying and plucking as much treasure as they can from the mountain, whose name means Rich Hill. That raises a larger specter of not only geologic but human loss, especially since the Bolivian government doesn't seem to be able to stop mining activity there. "I am a miner," says Morales, shrugging as he hunches down into his oxygen-scarce tunnel. "What else am I supposed to do?"

Indeed, for five centuries mining has been just about the only thing to do in Potosí, Bolivia, the city just beneath Cerro Rico that was once the western hemisphere's richest -- a 17th-century Paris of the New World. The Cerro's silver funded Spain's colonial empire, and when the Spanish left in the 19th century, Potosinos started mining the mountain for themselves. Their earnings, however, have been minimal. Still, although Potosí is today the poorest state in the poorest country in South America, mining is what keeps the population afloat financially: more than half the city's 150,000 residents depend directly on the mines for their livelihoods.

Mining safety is a more acute issue today, especially after the Chilean mine rescue drama watched around the globe last year. Each day millions of people worldwide risk their lives underground for metals, coal and precious stones, and each year thousands are killed, often in the very cave-ins now threatening Cerro Rico -- which is hardly a model of operational safety. It's more like a mammoth anthill with more than 650 separate, barely regulated entrances and hundreds of thousands of passageways that follow depleting zinc, tin and silver veins. Experts say infrastructure and machinery there are at least half a century behind the rest of the world: miners normally descend three-story shafts by harness and rope with pick-axes in hand; passageways are buttressed by rotting planks and, in some tunnels, toxic gas stings the eyes within minutes and can cause lung and muscle paralysis in a few hours.

Cerro Rico is already hundreds of meters shorter than it was when the Spanish first spotted it in 1545. "This is not about the whole mountain collapsing at once," says Hugo Delgado, lead researcher at the Cerro for Bolivia's National Geologic & Technical Mining Service. "But there are numerous zones of major risk that ought to have limited operations to avoid serious collapses." So far the warnings have fallen mostly on deaf ears. "We are going to keep working the Cerro until there is nothing left to mine," says Julio Quiñones, president of FEDECOMIN, an association of dozens of the more than 200 cooperatives, or small companies, that work the mountain.

And there's little to stop them. The government is largely hands-off on safety. Bolivia's state mining company, COMIBOL, owns the Cerro but licenses its operation to cooperatives and a handful of multinationals. "They are responsible for safety in their own houses," says Oscar Cáceres, a COMIBOL geologic engineer, explaining that the state is not liable for mine deaths or accidents. Cáceres' team polices the mountain, keeping people out of the "red zone" - the unstable peak that's been off-limits since 2009 -- and trying to ensure safety standards elsewhere. But with only 15 men to monitor 15,000 miners there, he admits they can't do much.

Haphazard mineral exploitation are partially responsible for the Cerro's current geologic instability. So, say geologists, are the open pit mines operated on the mountain's back side by the Canadian-owned San Bartolomé company. (San Bartolomé denies that.) "Collapses will increase because of the inadequate mining techniques currently being used," says Delgado, who urges cooperative owners to strengthen tunnel infrastructure and modernize extraction methods. But in Potosí it's common knowledge that some miners are now purposely provoking collapses within the Cerro's spinal column, a tin-rich shaft the Spanish failed to empty, because it's easy access to profitable rock.

It might seem more logical for cooperative owners to extend the lifespan of the source of their income. But logic often has little to do with the workings inside the Cerro. Nor does God exist there, according to miners like Morales; instead, a spiritual compañero, or companion, known as Tío, or Uncle, presides. A collapse or accident, they say, occurs only because Tio has been angered. Likewise, finding a plentiful vein is Tío's blessing. "What happens inside depends on Mother Earth and Tío," Quiñones tells TIME. Which is why the miners also lower down daily offerings of coca leaves to the devil-like statues of Tío, which to them are more important than wearing masks or monitoring gas levels. "Gracias, Tío," Morales says as he brings his own leaves to a statue in his mine adorned with colored paper, cigarettes and bottles of grain alcohol.

That faith, in a cynical sense, is good business for cooperative owners like Quiñones, since they feel little labor pressure to invest in tunnel improvements. The Potosí government, meanwhile, is looking for nearby mineral deposits to relocate mine workers. But even state Mining Secretary Arnulfo Gutíerrez admits that miners won't abandon the Cerro until its riches run out or the mountain falls. Miners like Morales, whose three-generation household has 11 mouths to feed, are working 16-hour shifts these days to take advantage of high mineral prices. Morales knows the rush aggravates the mountain's fragility; his high-activity mine is especially ripe for collapse. He also knows Cerro Rico is called "the mountain that eats men" for the millions of miners (many of them slaves) killed there over the centuries. "You know, there's another bridge that could be built from here to Spain," he concedes. "One made from the bones of miners who have died inside here."

But he keeps descending, offering cigarettes and coca. What else is he supposed to do?